The goal of this project is to understand mechanisms of spontaneous and induced neoplastic transformation in cultured mammalian cells with emphasis on the use of human cells, particularly those of epithelial origin. The primary approaches are to characterize the environmental conditions that control and promote transformation and to determine the effect of some of these environmental factors on chromosome aberrations, DNA damage and repair of that damage. Other efforts are aimed at identifying characteristics of cells in culture which specifically correlate with their neoplastic potential in vivo.